Large scale biomimetic membrane arrays

To establish planar biomimetic membranes across large scale partition aperture arrays, we created a disposable single-use horizontal chamber design that supports combined optical–electrical measurements. Functional lipid bilayers could easily and efficiently be established across CO₂ laser micro-structured 8?×?8 aperture partition arrays with average aperture diameters of 301?±?5 μm. We addressed the electro-physical properties of the lipid bilayers established across the micro-structured scaffold arrays by controllable reconstitution of biotechnological and physiological relevant membrane peptides and proteins. Next, we tested the scalability of the biomimetic membrane design by establishing lipid bilayers in rectangular 24?×?24 and hexagonal 24?×?27 aperture arrays, respectively. The results presented show that the design is suitable for further developments of sensitive biosensor assays, and furthermore demonstrate that the design can conveniently be scaled up to support planar lipid bilayers in large square-centimeter partition arrays.

[UF6]2−: A Molecular Hexafluorido Actinide(IV) Complex with Compensating Spin and Orbital Magnetic Moments

The first structurally characterized hexafluorido complex of a tetravalent actinide ion, the [UF₆]^2? anion, is reported in the (NEt₄)₂[UF₆]?2 H₂O salt ( 1 ). The weak magnetic response of 1 results from both U^IV spin and orbital contributions, as established by combining X‐ray magnetic circular dichroism (XMCD) spectroscopy and bulk magnetization measurements. The spin and orbital moments are virtually identical in magnitude, but opposite in sign, resulting in an almost perfect cancellation, which is corroborated by ab initio calculations. This work constitutes the first experimental demonstration of a seemingly non‐magnetic molecular actinide complex carrying sizable spin and orbital magnetic moments.     

Boundary Chromatic Polynomial

We consider proper colorings of planar graphs embedded in the annulus, such that vertices on one rim can take Q _s colors, while all remaining vertices can take Q colors. The corresponding chromatic polynomial is related to the partition function of a boundary loop model. Using results for the latter, the phase diagram of the coloring problem (with real Q and Q _s) is inferred, in the limits of two-dimensional or quasi one-dimensional infinite graphs. We find in particular that the special role played by Beraha numbers for the usual chromatic polynomial does not extend to the case Q≠Q _s. The agreement with (scarce) existing numerical results is perfect; further numerical checks are presented here.     

Julius Petersen annotated bibliography

This is the first comprehensive bibliography of Julius Petersen's papers and books, covering not only his mathematical works, but also his contributions to economics, social science, physics and education.     

The effect of transformation-defective avian oncornavirus mutants on tumor antigen expression.

The recent isolation of conditional (temperature sensitive) and nonconditional transformation-defective mutants of avian sarcoma virus strains has facilitated the investigation of the effect of virus transformation on the cell's phenotype, e.g., with respect to morphology, growth pattern, or cell surface antigenicity. Special emphasis was laid on elucidating the correlation between transformed phenotype and tumor antigen expression. All of the tested nontransforming deletion mutants and the majority of the temperature-sensitive mutants were unable to induce tumor antigens in phenotypically untransformed cells. However, 3 temperature-sensitive mutants were found which were able to support the expression of tumor specific surface antigens even at restrictive temperature, when cells otherwise exhibited a normal phenotype. The theoretical and practical implications of this association between normal phenotype and tumor antigen expression are discussed.